Optimization of Turbo Decoding Performance in the Presence of Impulsive Noise Using Soft Limitation at the Receiver Side

The impulsive noise is one of the main reasons for bit or burst errors in power line transmission. The use of a level limiter is a simple and intuitive technique to mitigate the noxious effect of impulsive noise in such channels. However the appropriate threshold determination remains empirical. In this paper, a suitable calculation of the log-likelihood ratio (LLR) for Turbo codes (TC) in an impulsive environment is performed both for BPSK and OFDM systems. As main results of the present work, we first determine the LLR channel value when using a limiter. Furthermore, based on a receiver operating characteristic (ROC) analysis, we derive the optimal detection threshold of the limiter. Finally, the results are validated by simulation with HomePlug AV physical layer specification.